Airbag system

ABSTRACT

An airbag module for a vehicle includes an airbag cushion, an inflator to inflate the airbag cushion, a sleeve connected to the airbag cushion and a tether configured to pass through the sleeve. A first end of the tether is anchored to a portion of the airbag cushion, module, or a structure of the vehicle and a second, opposite end of the tether is capable of passing through at least a portion of the sleeve during deployment of the airbag. The tether and sleeve are configured to initially restrain the deployment of the airbag cushion to provide a knee bolster, after which the tether is configured to unlace within the sleeve to release the restraint on the airbag cushion.

BACKGROUND

The present invention relates generally to the field of airbags. Morespecifically, the present invention relates to knee, chest and headairbags using a tether and sleeve to control the shape of an airbagduring inflation.

Airbags are provided in vehicles to protect occupants from injury in theevent of a vehicle crash. Knee airbags in particular help prevent thelegs of occupants from injury by preventing the legs from hitting thedash or an instrument panel in the event of a frontal crash.

Under certain circumstances, it is desirable to deploy a vehicle airbagin what is known as a “low risk deployment” (LRD) mode. LRD modes aretypically required when there is a chance that a deploying airbag maycontact an out-of-position (“OOP”) occupant or, in certain cases, a rearfacing infant seat (RFIS). Typically, airbag systems are designed withelectronic occupant sensing systems or airbag suppression mechanismscombined with appropriate inflator output controls to avoid suchsituations.

Conventional airbag systems either proposed or in production employ someform of vent in the airbag cushion or module which are mechanicallylinked to an active or passive release system. Other conventional airbagsystems also employ some form of bag restraint tether alone or incombination with a venting system.

In light of the above, there remains a continuing need in the art forimproved airbag systems that are simple in design and easy to operate.There is also a need in the art for improved airbag systems that exhibitimproved performance. Moreover, there is a need in the art for an airbagsystem that will still be filled with relatively high pressure inflationgas which would offer significant occupant impact protection, eventhough the airbag cushion may not have deployed to a full volume beforebeing impacted by an occupant.

SUMMARY

One exemplary embodiment relates to an airbag module for a vehicleincluding an airbag cushion, an inflator to inflate the airbag cushion,a sleeve connected to the airbag cushion and a tether configured to passthrough the sleeve. A first end of the tether is anchored to a portionof the airbag cushion, module, or a structure of the vehicle and asecond, opposite end of the tether is capable of passing through atleast a portion of the sleeve during deployment of the airbag. Thetether and sleeve are configured to initially restrain the deployment ofthe airbag cushion to provide a knee bolster, after which the tether isconfigured to unlace within the sleeve to release the restraint on theairbag cushion.

Another exemplary embodiment relates to an airbag module for a vehicleincluding an airbag cushion having a first portion and a second portionlarger than the first portion. The airbag module also includes aninflator provided in fluid communication with the airbag cushion. Theairbag cushion is deployed initially in a restrained state so that onlythe first portion of the airbag cushion is inflated upon initialdeployment of the airbag cushion until the airbag unlaces to deploy thesecond portion of the airbag cushion. The first portion is configured toprovide protection to the knees of an occupant and the second portion ofthe airbag cushion is configured to provide protection to the upper bodyof the occupant.

Another exemplary embodiment relates to an airbag system for protectinga vehicle occupant including an airbag cushion having a first portionand a second portion larger than the first portion and an inflator toinflate the airbag cushion. The airbag system also includes a housingprovided in a lower portion of a dash of the vehicle and configured toreceive the airbag cushion in an un-deployed state. The airbag isdeployed in a restrained state such that only the first portion of theairbag is inflated to provide protection to the knees of the occupant,after which the airbag unlaces to deploy the second portion of theairbag in combination with the first portion of the airbag to provideprotection to the occupant.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory only,and are not restrictive of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features, aspects, and advantages of the presentinvention will become apparent from the following description, appendedclaims, and the accompanying exemplary embodiments shown in thedrawings, which are briefly described below.

FIG. 1 is a diagram which shows an airbag module with a single internaltether.

FIG. 2( a) shows the cross sectional view of the airbag moduleillustrated in FIG. 1 according to an embodiment.

FIG. 2( b) shows the cross sectional view of the airbag module of FIG. 1in which an alternate arrangement of the tether is shown.

FIG. 3 is a diagram which shows an airbag module incorporating multipleinternal tethers having single or multiple release points.

FIG. 4 is a diagram which shows an airbag module incorporating a band orstrap configuration tether having single or multiple release points.

FIG. 5 shows a pyro-technic hold-release mechanism.

FIG. 6 is a diagram which shows the cross sectional view of thepyro-technic hold release mechanism illustrated in FIG. 5 with a fabrictether in a clamped position.

FIG. 7 is a diagram which shows an alternative embodiment of ahold-release mechanism.

FIG. 8 is a cross sectional view of an airbag module incorporating amechanical tether release.

FIG. 9 is a view of an airbag during initial stages of inflationillustrating a tether and sleeve restraining the airbag according toanother embodiment.

FIG. 10 is a view of the airbag of FIG. 9 in which the tether has beenreleased and the airbag has fully inflated.

FIG. 11 is an internal view of the airbag of FIG. 9 illustrating thetether and sleeve restraining the airbag.

FIG. 12 is an external view of the airbag of FIG. 9 illustrating thetether and sleeve restraining the airbag.

FIG. 13 is an external view of the airbag of FIG. 9 after the tether hasbeen released from the sleeve.

FIG. 14 is an interior view of a portion of an airbag cushion accordingto another embodiment in which a sleeve is shown.

FIG. 15 is an exterior view of the portion of the airbag cushion of FIG.14 in which an anchor of a tether is shown.

FIG. 16 illustrates a top plan view of a fabric panel for forming anairbag cushion according to another embodiment in which a tether andsleeve are shown.

FIG. 17 illustrates a top plan view of a fabric panel for forming anairbag cushion according to another embodiment in which a sleeve isshown.

FIG. 18 illustrates a exterior view of a portion of an airbag cushion inwhich an approximate “Y” shaped sleeve is illustrated.

FIG. 19 illustrates an interior view of a portion of an airbag cushionaccording to another embodiment in which a sleeve and wider tether areshown.

FIG. 20 illustrates an interior view of a portion of an airbag cushionaccording to another embodiment in which an overlapping sleeve andtethers are shown.

FIG. 21 is an interior perspective view of a vehicle having an airbagmodule according to an exemplary embodiment.

FIG. 22( a) is an illustration of a side view of an airbag after initialdeployment according to an exemplary embodiment.

FIG. 22( b) is an illustration of a top view of the airbag shown in FIG.22( a).

FIG. 23 is an illustration of a side view of the airbag of FIG. 22( a)after further deployment according to an exemplary embodiment.

FIG. 24 is an illustration of a side view of the airbag shown in FIG.22( a) after further deployment according to an exemplary embodiment.

FIG. 25 is an illustration of a side view of the airbag shown in FIG.22( a) after further deployment according to an exemplary embodiment.

FIG. 26 is a chart of occupant energy absorbed over time for aconventional airbag system.

FIG. 27 is a chart of occupant energy absorbed over time for theembodiments shown in FIGS. 21-25.

DETAILED DESCRIPTION

Various disclosed embodiments address the problems described above andrelate to a low risk deployment device such as an airbag module whichemploys a controllable cushion shaped restraint tether to modify theperformance characteristics of the vehicle airbag. The airbag moduleincludes a housing, an inflatable airbag cushion being stored in anun-deployed position in the housing and an inflator that inflates theairbag cushion. The inflator is in communication with the airbagcushion. A tether element is provided surrounding an inside portion ofthe airbag cushion and restrains the airbag cushion during an initialdeployment. A control mechanism is provided to release the tetherelement.

One aspect relates to an airbag cushion (sometimes referred to as“airbag” or “cushion”) that uses a cushion shaping sleeve and apyrotechnically controlled tether combination to modify the deploymentcharacteristics of the cushion.

FIGS. 1-8 illustrate a first aspect of exemplary embodiments. FIG. 1 isa diagram which shows an airbag module with a single internal tetheraccording to one exemplary embodiment. As illustrated, the airbag moduleincludes a housing 12 and an inflatable airbag cushion 11. When notinflated, the airbag cushion 11 is provided within the housing 12.

By way of example only, and not a limitation, the airbag cushion 11 maybe a standard airbag cushion or a cushion including multiple lobes orinflatable chmbers such as, for example, a twin or dual lobe typecushion. The airbag cushion 11 is provided with an internal tether 10.It is to be understood that the internal tether 10 may be formed in amanner such that the airbag cushion 11 is restrained during an initialdeployment to provide a low risk deployment function. Thus, by way ofexample as illustrated in FIG. 1, the internal tether 10 surrounds acentral section of the airbag cushion 11 and restrains the airbagcushion 11 during an initial deployment to provide the low riskdeployment function. Alternatively, the internal tether 10 may surroundan offset section of the airbag cushion 11 to provide the same low riskdeployment function. Alternatively, the tether 10 may be in asubstantially horizontal position.

Referring to FIG. 2( a), a diagram of the cross sectional view of theairbag module illustrated in FIG. 1 is illustrated. As shown, the airbagmodule is provided in a “mid-mount” position (in the instrument panel)and further includes tether guide loops 20 provided inside the airbagcushion 11, a tether anchor point 21, an inflator 23, and tetherreleases 24 and 25 which are provided inside or outside of the airbagmodule. As illustrated, the airbag cushion 11 is held in communicationwith the inflator 23. The mid-mount position is exemplary only. Thestructure and arrangement of the module may be applicable to otherpositions such as, for example, a top mount position in which the airbagdeploys out of the top of the instrument panel.

According to another embodiment, such as shown in FIG. 2( b), the tether10 may be routed such that it does not follow the inner contour or shapeof the airbag cushion. Rather, the tether 10 may be routed in a zig-zagor alternating manner, such as indicated by the arrows in FIG. 2( b),inside the airbag cushion 11 to provide restraint at various points.This zig-zag route allows a variety of restrained airbag shapes to berealized based on the tether routing employed. Various portions of theairbag cushion 11 can be restrained or allowed to bulge depending on theperformance requirements. FIG. 2( b) illustrates one exemplary route ofthe tether 10. It will be recognized that the tether may follow anyother suitable route.

According to an embodiment, the internal tether 10 may be released oractivated by a variety of passive or active control techniques. By wayof example only, the internal tether 10 may be passively released by avariety of devices which release or cut the internal tether 10 throughthe use of a secondary control tether or release cord mounted within theairbag cushion 11 or which are an integral part of the airbag cushion 11as explained in greater detail below. Alternatively, the internal tether10 may be actively released by a dual stage inflator gas cutting or amicro-gas generator (MGG) cut or release mechanism. The MGG may beactivated by simple timer, a velocity sensor, an occupant sensing systemor any other similar control system.

Referring to FIGS. 3 and 4, these figures illustrate alternativeembodiments of an airbag module. As illustrated in FIG. 3, the twointernal tethers 30 and 31 are provided around the inside of the airbagcushion 11. The two internal tethers 30 and 31 may include a single ormultiple release points. While the exemplary airbag cushion 11 includestwo internal tethers 30 and 31, it is to be understood that the numberof internal tethers in no way limits the present disclosure.Accordingly, it is to be understood that the disclosed airbags will haveequal applicability three or more internal tethers.

FIG. 4 illustrates another alternative embodiment of an airbag moduleincorporating a band or strap configuration as the internal tether 40.The band or strap configuration for the internal tether 40 may include asingle or multiple release points. While the exemplary airbag cushionincludes a band or strap configuration for the internal tether 40, it isto be understood that the material used is in no way limiting.Accordingly, it is to be understood that the airbag tether may haveequal applicability using a variety of materials including for example,cables, straps, cords, etc.

FIG. 5 illustrates a pyro-technic hold-release mechanism according toone embodiment of the present invention. The pyro-technic hold-releasemechanism includes a pyro housing 51, a clamp section 52, aconnector/wiring 50 and hook/clamp 55. A fabric tether 53 protrudes froma tether exit hole 54 of the housing 12. The fabric tether 53 is thenprovided through the hook/clamp 55. As illustrated, the hook/clamp 55 isin a released or unclamped position.

FIG. 6 is a diagram which shows the cross sectional view of thepyro-technic hold-release mechanism illustrated in FIG. 5 with thefabric tether in a clamped position. As illustrated, the pyro-technichold-release mechanism is in the tether clamped position with the fabrictether 53 clamped by the clamp section 52. Reference numeral 61 showsthe clamped area of the fabric tether 53. Provided within the pyrohousing 51 is a piston area 60 which is part of the hook/clamp 55.

FIG. 7 is a diagram which shows an alternative embodiment of ahold-release mechanism. As shown, the hold-release mechanism furtherincludes a pin-steel roll travel limiting 71 provided on two sides ofthe piston area 60 and a holder housing initiator 72, provided on anupper portion of the piston area 60 near the hook/clamp 55. A holderhousing initiator 72 is provided at an opposite end of the clamp section52.

Referring to FIG. 8, an exemplary construction of an airbag moduleincorporating a mechanical tether release according to an alternativeembodiment is shown. The mechanical tether release is a passive,excursion based tether internal to the airbag cushion 11 and may beemployed in an airbag module which is not operated in combination withan occupant sensing or detection system. This cross-sectional view ofthe airbag module incorporates a secondary release tether 80 terminatingat one end in a loop formed in the airbag cushion 11 and terminating atthe other end around a restraining pin 82. The restraining pin 82 isprovided to secure one end of the internal tether 10 (the end oppositethe tether anchor point 21) and the secondary release tether 80 to eachother. As illustrated, the airbag cushion 11 is in a deployed state. Thesecondary release tether 80 becomes taught which pulls the restrainingpin 82 out of engagement with the internal “control” tether 10, therebyallowing the airbag cushion 11 to continue expanding to full size.

FIGS. 9-13 illustrate another embodiment of an airbag system. The airbagsystem includes an airbag cushion 100 formed of at least one fabricpanel, an inflator (such as shown in FIG. 2( a)), a tether 130 laced orthreaded through a sleeve 140.

An airbag cushion 100 to protect an occupant in a vehicle may beinstalled in a vehicle body part, such as a dashboard, steering wheel,steering column, roof line or A, B, or C columns in a vehicle. FIG. 9illustrates an airbag cushion 100 that is installed in a dashboard of avehicle in which the airbag cushion 100 is shown during initial stagesof inflation. The airbag cushion 100 includes at least one fabric panel.For example, as shown in FIGS. 9-13, the airbag cushion 100 includes acenter fabric panel 110 and left and right fabric panels 120. The fabricpanels may comprise any suitable material. The fabric panels 110, 120are sewn together by sewn seams 115. Alternatively, the airbag cushion100 may be formed of any number of fabric panels.

The sleeve 140 is formed by a piece of fabric, such as airbag panelmaterial, that is attached to an inside surface of the center fabricpanel 110 by sewn seams 135, such as shown in FIG. 11. The sleeve 140includes an opening 145 through which the tether 130 may be inserted.The sleeve 140 can be a continuous piece that is connected to the centerfabric panel 110 at one end or the sleeve can comprise multiple shortsleeves or loops (“belt loop” version). The sleeve 140 can extend fromone end near the inflator to an opposite end at a second location on thefabric panel 110. Alternatively, the sleeve 140 may be connected to oneof the side panels 120, or to a plurality of panels 110, 120 dependingon desired cushion kinematics.

In embodiments, the sleeve 140 and tether 130 combination can be locatedon the center panel 110 or the side panel(s) 120 of the airbag cushion100 and the combination 140, 130 is used initially to severely restrictthe cushion 100 volume. More than one sleeve/tether 140, 130 combinationcan be used depending on the desired cushion 100 kinematics. The sleeve140 can be constructed of fabric, film, polymer, or other suitablematerial in a continuous or segmented (open) fashion, and can vary inlength and width depending on the desired cushion kinematics. When thesleeve 140 comprises multiple short segments, the combined lengths ofthe individual short segments determine the cumulative sleeve length.

The tether 130 is positioned between an inner surface of the fabricpanel 110 and an inner surface of the sleeve 140. The tether 130, asshown, is one continuous tether. Alternatively, the tether 130 may besegmented. In the example shown, one end of the tether 130 is fixed (bysewing or any other suitable mechanism) to the airbag cushion 100. Theopposite end of the tether 130 is connected to a release pin (notshown). The opposite end of the tether 130 may include a loop thatconnects to the release pin. The release pin is located on or near theinflator (alternatively, the release pin may be located elsewhere in theairbag system).

The tether 130 can be constructed of fabric, webbing, elastic “bungee”type material, rope, cord, or other suitable material. The tether 130can vary in length and width. The attachment point of the fixed end canvary depending on the desired cushion 100 kinematics. The tether 130 isrouted through the sleeve 140 and the releasable end (opposite end) isattached to a pyrotechnically actuated release mechanism (release pin),such as for example, the release mechanisms shown in FIGS. 5-8. Therelease pin, alternatively, may be electro-mechanically triggered torelease.

During inflation of the airbag cushion 100, the combination of thetether 130 and sleeve 140 cinch or restrain the shape of the airbagcushion 100. For example, as seen in FIG. 9, the airbag cushion 100forms a split configuration during initial stages of inflation.Depending on the data determined by one or more sensors or on theprogram of the inflator's controller, the release pin is shifted, thusreleasing the loop end of the tether 130. When the loop end of thetether 130 is released, the tether 130 slides through (“unlaces”) withinthe sleeve 140 and the airbag cushion 100 is no longer restrained or“cinched.” Thus, the airbag cushion 100 is allowed to reach a fullyinflated shaped, such as shown in FIG. 10.

The time at which the release pin is shifted can vary depending on anynumber of factors. For example, the release time can be preset.Alternatively, the release time can vary depending upon the findings ofvarious sensors.

The initial restriction of the airbag cushion 100 volume limits the“punch out” force that may otherwise occur early in deployment. Therearward excursion of the airbag cushion 100 is also minimized by therestrictive tether 130. Additionally, the restricted volume aids inearly venting of inflation gas, which is beneficial in an OOPdeployment. As the airbag cushion 100 is initially deployed in a greatlyrestricted state with its shape controlled by the sleeve 140 and tether130, the requirement for any type of controlled folding can be negated.The restricted airbag cushion 100 can be in its initially “breakout”position and venting gas within approximately ten milliseconds of thestart of the deployment. Although not shown, the various embodiments ofrestraining systems disclosed herein may be used in combination with aventing system such as disclosed for example, in U.S. patent applicationSer. No. 11/523,810, which is incorporated by reference herein.

At a time that can be adjusted depending on the environment, the tether130 is released and begins unlacing through the cushion shaping sleeve140. The release of the tether 140 causes an immediate increase incushion volume with an attendant drop in pressure, resulting in lowerforces being exerted on the occupants in OOP situations.

The “unlacing” (sliding release of tether 130 through the sleeve 140)phenomenon of the tether 130 acting within the sleeve shapes the airbagcushion 100 and causes it to dive down. Cushion kinematics show verylittle variation, resulting in improved restraint performance of theairbag cushion 100 for all occupant sizes (for example, 5% female to 95%male).

FIGS. 11 and 12 illustrate the airbag cushion 100 when cinched. FIG. 11is a view of the airbag cushion 100 inside-out (an internal view). FIG.12 is an external view of the airbag cushion 100. FIG. 13 is a view ofthe airbag cushion 100 after the tether has been released and the airbagcushion 100 is laying flat.

FIGS. 14-20 illustrate another aspect of exemplary embodiments in whicha cushion shaping sleeve 240 and controlling tether 230 combinationmodify the deployment characteristics of an airbag cushion 200. Thesleeve 240 and tether 230 may be located at any location of the airbagcushion 200. For example, the sleeve 240 and tether 230 can bepositioned on a center or side panel of the airbag cushion 200. Further,the sleeve 240 and tether 230 may be positioned on an interior orexterior of the airbag cushion 200. In the Figures, the sleeve 240 andtether 230 are shown in the interior position for exemplary purposesonly.

FIG. 14 illustrates an inside view of a fabric panel forming an airbagcushion 200. The sleeve 240 is formed by a panel of fabric, film,polymer, or other suitable material that is attached to the inside ofthe airbag cushion 200 view sewn seams 235. The sleeve 240 can vary inlength and width and may be formed of segmented components or the sleeve240 may be continuous.

The tether 230 (shown in FIGS. 16-17 and 19-20) is formed of a length,preferably a continuous length, of fabric, webbing, elastic, rope, cord,or other suitable material. One end of the tether 230 is anchored orattached to the airbag cushion 200 by sewn seams or any other suitableattachment mechanism, such as shown in FIG. 15. Alternatively, theanchored end of the tether 230 is anchored and/or connected to an airbagmodule or housing or vehicle structure either internally or externally.The tether 230 may also be integrated with the airbag cushion 200. Theopposite end 231 (see FIG. 19) is free. Thus, the tether 230 isconfigured to pass within the sleeve 240 with one end anchored to theairbag cushion 200 and an opposite end 231 free. Alternatively, the freeend 231 of the tether 230 may be anchored by a pyrotechnically actuatedrelease mechanism with a release pin passing through a loop at the end231 of the tether 230.

When the airbag cushion 200 deploys, the airbag cushion 200 begins toexpand, thus pulling the tether 230 through the sleeve 240. The lengthand width of the tether 230 and sleeve 240 vary the time for the free231 of the tether 230 to pass through the sleeve 240. When the tether230 is in the sleeve 240, the airbag cushion 200 is restrained at thatlocation. As the tether 230 moves through the sleeve 240 duringdeployment and the tether 230 unlaces from the sleeve 240, the excessmaterial of the tether 230 is forced to collapse on itself as it movesthrough the sleeve 240. This can result in higher frictional forces andcan slow the movement of the tether 230 through the sleeve 240. As thefrictional forces on the tether 230 are reduced, there is an increase incushion volume (thus, the airbag cushion 200 expands) with anaccompanying drop in pressure, thus resulting in lower forces that canbe exerted on an occupant in an OOP situation.

FIGS. 16-18 illustrate various configurations of the sleeve 240. Forexample, in FIG. 16, the sleeve 240 is a single, continuous lengthattached to the inside of the airbag cushion 200. The tether 230, inthis example, is shorter than the sleeve 240 and is shown inside thesleeve 240. FIG. 17 illustrates another embodiment of a sleeve 240 inwhich the sleeve 240 forms an approximate “V” shape. One, two, or moretethers 230 could pass through the sleeve, which could alter thedeployment characteristics of the airbag cushion 200. The multiple legsor components of the sleeve 240 form a serpentine path for the tether230. The number and location of the sleeve 240 components (or separatesleeves 240) can vary depending on desired airbag cushion 200kinematics. FIG. 18 illustrates a sleeve 260 that forms an approximate“Y” shape. In this example, two tethers may be utilized and anchored tothe airbag cushion 200 at anchor points 270.

In another embodiment, such as shown in FIG. 19, the width W_(T) of thetether 230 is greater than the functional width of the sleeve 240. Thefunctional width refers to the distance between the stitches 235 formingthe pocket of the sleeve 240. In FIG. 19, the tether 230 unlaces as itis drawn through the narrower sleeve 240. This results in higherfrictional forces and slows the movement of the tether 230 through thesleeve 240. Alternatively, the tether 230 can have varying widths, suchthat one portion of the tether 230 is narrower than the sleeve 240 andother portions that are wider than the sleeve 240.

FIG. 20 illustrates yet another exemplary embodiment in which the sleeve280 includes two overlapping portions 281, 282. A tether 291 passesthrough a sleeve portion 281. The tether 291 is doubled back on itselfand passes through a second sleeve portion 282. The tether 291 isnarrower than the width of the sleeve 280. Alternatively, the tether 291may be wider than the width of the sleeve 280 and/or its respectivesleeve portion 281 or 282. The serpentine path of the tether 291 resultsin higher frictional forces and can slow the movement of the tether 291through the sleeve 280.

According to embodiments, the length and width of the tether 230 andsleeve 240 can alter the deployment characteristics of the airbagcushion 200. For example, in an embodiment, the width W_(S) of thesleeve 240 must exceed the narrowest tether width Wt by at least afactor of 1.25. Further, the width W_(A) of the anchor must exceed thewidth W_(T) of the tether 230. In yet another example, if a release pinis utilized to initially restrain an end 231 of the tether 230, thetether loop diameter must exceed the retaining pin diameter by at leasta factor of 1.10.

For exemplary purposes only, the tether 230 may have an overall lengthof about 400 to 600 mm, or about 480 mm. In an embodiment, thefunctional tether 230 length which extends from an anchor point to aloop (or free end 231) can be 500 to 700 mm, or about 400 mm. The widthW_(S) of the sleeve 240 may be in a range of 20 to 80 mm, or about 40mm. The width W_(T) of the tether 230 may be in a range of 5 to 35 mm,or about 15 mm. The width W_(A) of the anchor of the tether 230 may bein a range of 30 to 80 mm, or about 60 mm. In an alternative embodiment,the cross-sectional area of the sleeve 240 does not increase duringdeployment of the airbag cushion 200.

According to an embodiment, the tether 230 and sleeve 240 may be locatedin any suitable location. For example, the sleeve 240 and tether 230 canbe internal to the airbag cushion 200 and the tether 230 can beconnected to a release mechanism inside the airbag cushion 200. In yetanother embodiment, the tether 230 and sleeve 240 are internal to theairbag cushion 200 and the second end 231 of the tether 230 is a free,unattached end. For another exemplary embodiment, the tether 230 andsleeve 240 are internal to the airbag cushion 200 and the tether 230 canbe connected to a release mechanism outside of the airbag cushion 200such that a portion of the tether 230 passes out of the airbag cushion200.

In alternative embodiments, the tether 230 and sleeve 240 are externalto the airbag cushion 200 and the tether 230 can be connected to arelease mechanism outside of the airbag cushion 200. Alternatively, thetether 230 and sleeve 240 are external to the airbag cushion 200 and thesecond end 231 of the tether 230 is a free, unattached end. In yetanother embodiment, the tether 230 and sleeve 240 are external to theairbag cushion 200 and the tether 230 can be connected to a releasemechanism inside of the airbag cushion 200 such that a portion of thetether 200 passes inside of the airbag cushion 200.

It will be recognized that any number of sleeves and/or tethers may beutilized. Further, the sleeve and tether may be positioned in anylocation on the airbag cushion and internal or external to the airbagcushion. For example, the sleeve and tether may be at a central oroffset location, in a vertical, horizontal, or diagonal position, or anycombination of the above. Further, any combination of theabove-mentioned tethers and sleeves may be utilized.

Embodiments can eliminate variability in airbag cushion kinematics thatcan be caused by fold variation. The control sleeve and tethereliminates the need to control the folding of the airbag cushion priorto deployment. Essentially any folding technique can be used withoutaffecting cushion trajectory or kinematics. Thus, embodiments canprovide predictable and repeatable airbag cushion kinematics. The“unlacing” phenomenon of the tether within the sleeve causes the cushionto “dive down” resulting in increased occupant protection for alloccupant sizes, such as for example, a 5th % female to a 95th % male.Multiple sleeve-tether combinations can be used to steer the airbagcushion, thus improving restraint performance in angular crashscenarios. For example, the tether and sleeve combination can allow theairbag cushion to be in an initial breakout position and venting gaswithin ten milliseconds of the start of the deployment.

Yet another advantage of embodiments is that the requirement forcontrolled folding is negated. The airbag cushion may be folded orrolled in any manner to place the airbag cushion in the housing. Thetether and sleeve combination control the deployment characteristics ofthe airbag cushion, not the specific fold method used.

Another possible advantage of embodiments is that airbag cushiondeployment variability can be minimized and a “low risk deployment” modecan be provided for out of position occupants and child seats withoutthe need for additional occupant classification sensors, buckleswitches, or other sensors.

Embodiments can eliminate the high energy “punch out” of the airbagcushion in the early stages of deployment and provides high and/or lowoutput capability with a single stage inflator.

The inflator to inflate the airbag cushion may be any suitable type ofinflator. For example, the inflator may be a single stage or a dualstage.

It will be recognized that the embodiments shown and described areexemplary only. For example, the tether and sleeve may be external suchthat they are attached to an outside surface of a fabric panel of theairbag.

It will be recognized that the airbag may be a single-lobe, dual-lobe,or any other suitable type of airbag. Furthermore, the airbag may be aknee airbag, driver-side, passenger-side or head-side airbag. The airbagmay be installed in any type of vehicle, such as an automobile, train,etc.

One exemplary embodiment of an airbag module includes the followingcomponents: a housing; an inflatable airbag cushion being stored in anun-deployed position in the housing; an inflator that inflates theairbag cushion and being in communication with the airbag cushion; atether element provided surrounding an inside portion of the airbagcushion and restrains the airbag cushion during an initial deployment;and a control mechanism to release the tether element. The module may bea “mid mount” module, referring to the mounting location in theinstrument panel of the vehicle.

The airbag cushion may be a twin lobe cushion. The position of thetether element surrounding the inside portion of the airbag cushion maybe selected from the group consisting of a central section of the airbagcushion and an offset section of the airbag cushion. The tether elementmay include multiple parts. The control mechanism may include a deviceto release the tether element using a control tether. Alternatively, thecontrol mechanism includes a dual stage inflator cutting. In anotherembodiment, the control mechanism may include a micro-gas generatorrelease mechanism. In such an embodiment, the micro-gas generatorrelease mechanism may be activated by a timer. Alternatively, themicro-gas generator release mechanism may be activated in response to asignal generated by a vehicle velocity sensor. In yet anotheralternative, the micro-gas generator release mechanism may be activatedin response to a signal generated by an occupant detection system. Inyet another alternative, the control mechanism may be a “passive”mechanism such that the deployment of the airbag itself controls themovement of the tether in the sleeve.

According to an embodiment, the tether element may be a cable or astrap. The airbag may include tether guide loops provided around aninside periphery of the airbag cushion to accommodate the tetherelement. Also, the airbag may include a tether anchor point to anchorone end of the tether element.

Referring now to FIGS. 21-25, another exemplary embodiment of an airbagmodule utilizing the above mentioned technology is shown. FIG. 21 showsan interior perspective of a vehicle 300 that includes an airbag module310 located in a lower dash 312 that is below the upper dash 314. In analternative embodiment, airbag module 310 may be located elsewhere invehicle 300 (e.g., in upper dash 314, etc.). Airbag module 310 mayinclude a housing 308 (as shown in FIGS. 22-25), an un-deployed airbagor cushion (not shown), and an inflator (not shown) in fluidcommunication with the cushion.

FIG. 22( a) illustrates a cushion 320 after initial deployment torestrain a vehicle occupant 302. A lower portion 322 of cushion 320 isshown to restrain the knees and/or lower body of the occupant 302. Thecushion 320 is deployed early in the event of a crash. The cushion 320is deployed in its restrained condition via a tether 316 as shown inFIG. 22( b), thus lower portion 322 of cushion 320 acts as an inflatableknee bolster.

FIG. 22( b) illustrates a top view of the airbag module 310 as shown inFIG. 22( a). The cushion 320 is restrained by tether 316 so that thelower portion 322 of the cushion 320 provides protection to the knees ofoccupant 302. The relatively small volume of lower portion 322 ofcushion 320 will provide a high pressure airbag to keep the pelvis ofthe occupant 302 restrained in a vehicle seat (not shown), regardless ofthe seatbelt usage of the occupant 302.

Once the pelvis of the occupant 302 has been restrained, the cushion 320will then unlace to deploy an upper portion 324 of cushion 320 so thatthe cushion 320 now occupies a larger volume, as illustrated in FIG. 23.Occupant 302, whose pelvis has been restrained, will then pivot into thefully inflated cushion 320. The additional volume of the upper portion324 of cushion 320 reduces the overall air pressure inside the cushion320, thus reducing the punch out effect of a high pressure airbag, aspreviously discussed.

FIG. 24 illustrates an alternative embodiment of the airbag module 310in that the housing is modified so that the upper portion 324 of thecushion 320 inflates out of the upper dash 314. In this embodiment, thelower portion 322 of cushion 320 inflates out of the lower dash 312towards the occupant 302 to restrain the knees and pelvis of theoccupant 302 as illustrated in FIGS. 22( a)-22(b). The cushion 320 thenunlaces (to its second volume) to deploy the upper portion 324 ofcushion 320 to offer head and/or upper torso protection to occupant 302.The upper portion 324 of cushion 320 inflates between the windshield andthe head and/or upper torso of the occupant 302. In an alternativeembodiment, the airbag module 310 may be located elsewhere in the dash.In another alternative embodiment, the dash (rather than just thehousing) may be modified to allow the upper portion 324 of cushion 320to inflate out the top of the dash. In yet another alternativeembodiment, the dash and the housing may be modified to allow the upperportion 324 of cushion 320 to inflate out the top of the dash.

FIG. 25 illustrates yet another alternative embodiment of the airbagmodule 310 including a second airbag module 311 having a second airbagor cushion 321 inflating out of the upper dash 314. In this embodiment,the first cushion 320 inflates out of the lower dash 312 towards theoccupant 302 to restrain the knees and pelvis of the occupant 302 asillustrated in FIGS. 22( a)-22(b). The first cushion 320 then unlaces toits second volume with upper portion 324 of cushion 320 to offer uppertorso protection to occupant 302. At the same time as the first cushion320 unlaces, the second cushion 321 inflates between the windshield andthe head of the occupant 302. In this embodiment, the first cushion 320and second cushion 321 function as one overall unit as the occupant 302pivots into cushions 320, 321. In an alternative embodiment, secondcushion 321 may inflate either before or after the unlacing of the firstcushion 320.

In the above embodiments shown in FIGS. 22-25, the inflator (not shown)could be a single stage inflator. Alternatively, the inflator could be amulti-stage inflator used to inflate the lower portion 322 of cushion320 with a first stage and to inflate the upper portion 324 of cushion320 with a second stage. The multi-stage inflator would allow moretuning or refinement to be done to the pressure inside the lower andupper portions 322, 324 of cushion 320 and how long and/or how muchpressure exists in each of the portions 322, 324 of cushion 320 duringthe deployment of the airbag cushion 320. In yet another alternativeembodiment, a gas diffuser (not shown) may be used to direct a certainpercentage of gas into each portion 322, 324 of the cushion 320.

One advantage of the embodiments shown in FIGS. 22-25 is that the designis compatible with OOP and RFIS requirements. When the smallerrestrained lower portion 322 of cushion 320 is initially deployed, itwill load the OOP occupant's pelvis/abdomen and push the occupant off ofthe dash or instrument panel before the cushion 320 has had a chance tounlace and come into contact with the occupant's head and/or neck. In aRFIS situation, when the smaller lower portion 322 of cushion 320deploys, it will come into contact with the sturdy base of the infantseat, and start to push the child restraining system (CRS) back and outof the way by the time that the cushion 320 unlaces.

From an energy management viewpoint, the embodiments shown in FIGS.22-25 will eliminate more energy early on in the event of a crash asshown in FIG. 27 as compared to a conventional system as shown in FIG.26. Airbag module 310 will limit the forward movement of an occupant'spelvis relative to the vehicle, allowing the occupant to dissipate moreenergy through vehicle ride down. With more energy dissipated up front,the upper portion 324 of cushion 320 does not have to be as large as ina conventional airbag system. This is because there will be less energyto absorb as the occupant will be pivoting down into the airbag orcushion instead of translating up into the airbag as in a conventionaldesign.

Given the disclosure of the present invention, one versed in the artwould appreciate that there may be other embodiments and modificationswithin the scope and spirit of the invention. Accordingly, allmodifications attainable by one versed in the art from the presentdisclosure within the scope and spirit of the present invention are tobe included as further embodiments of the present invention. The scopeof the present invention is to be defined as set forth in the followingclaims.

1. An airbag module for a vehicle, comprising: an airbag cushion; aninflator to inflate the airbag cushion; a sleeve connected to the airbagcushion; and a tether configured to pass through the sleeve, wherein afirst end of the tether is anchored to a portion of the airbag cushion,module, or a structure of the vehicle and a second, opposite end of thetether is capable of passing through at least a portion of the sleeveduring deployment of the airbag, wherein the tether and sleeve areconfigured to initially restrain the deployment of the airbag cushion toprovide a knee bolster, after which the tether is configured to unlacewithin the sleeve to release the restraint on the airbag cushion.
 2. Theairbag module of claim 1, further comprising a housing located in alower portion of a dash of the vehicle and configured to receive theairbag cushion in an un-deployed state.
 3. The airbag module of claim 1,wherein the airbag is configured to deploy into a position that providesprotection to the knees of an occupant and also restrains a pelvis ofthe occupant.
 4. The airbag module of claim 1, wherein a first portionof the airbag cushion deploys out of a lower portion of a dash of thevehicle and a second portion of the airbag cushion deploys out an upperportion of the dash of the vehicle after the tether unlaces from thesleeve.
 5. The airbag module of claim 1, further comprising a secondairbag cushion, wherein the first airbag cushion deploys out a lowerportion of a dash of the vehicle and the second cushion deploys out anupper portion of the dash of the vehicle.
 6. The airbag cushion of claim5, wherein the first airbag cushion and the second airbag cushionfunction as one over all airbag system.
 7. The airbag module of claim 6,wherein the second airbag cushion deploys after the first airbag cushionhas unlaced.
 8. The airbag module of claim 6, wherein a second airbagcushion deploys at the same time as the first airbag cushion unlaces. 9.An airbag module for a vehicle, comprising: an airbag cushion having afirst portion and a second portion larger than the first portion; aninflator provided in fluid communication with the airbag cushion;wherein the airbag cushion is deployed initially in a restrained stateso that only the first portion of the airbag cushion is inflated uponinitial deployment of the airbag cushion until the airbag unlaces todeploy the second portion of the airbag cushion; wherein the firstportion is configured to provide protection to the knees of an occupantand the second portion of the airbag cushion is configured to provideprotection to the upper body of the occupant.
 10. The airbag module ofclaim 9, wherein the second portion of the airbag cushion inflates to alower pressure than the first portion during the restrained state of theairbag cushion.
 11. The airbag module of claim 9, wherein the inflatoris a multi-stage inflator configured to inflate the first portion of theairbag cushion with a first stage and the second portion of the airbagcushion with a second stage.
 12. The airbag module of claim 9, furthercomprising a housing located in a lower portion in a dash of the vehicleand configured to receive the airbag cushion in an un-deployed state.13. The airbag module of claim 9, wherein the first portion of theairbag cushion deploys out the lower portion of a dash of the vehicleand a second portion of the airbag cushion deploys out an upper portionof the dash of the vehicle after a tether unlaces from a sleeve.
 14. Theairbag module of claim 9, further comprising a second airbag cushion,wherein the first airbag cushion deploys out a lower portion of a dashof the vehicle and the second cushion deploys out an upper portion ofthe dash of the vehicle.
 15. The airbag module of claim 14, wherein thefirst airbag cushion and the second airbag cushion function as anintegral airbag system.
 16. An airbag system for protecting a vehicleoccupant comprising: an airbag cushion having a first portion and asecond portion larger than the first portion; an inflator to inflate theairbag cushion; a housing provided in a lower portion of a dash of thevehicle and configured to receive the airbag cushion in an un-deployedstate; wherein the airbag is deployed in a restrained state such thatonly the first portion of the airbag is inflated to provide protectionto the knees of the occupant, after which the airbag unlaces to deploythe second portion of the airbag in combination with the first portionof the airbag to provide protection to the occupant.
 17. The airbagsystem of claim 16, wherein the first portion of the airbag is providedat a first pressure upon initial deployment of the airbag and the firstand second portions of the airbag are provided at a second pressure uponunlacing of the airbag.
 18. The airbag assembly of claim 17, wherein thesecond pressure is lower than the first pressure.
 19. The airbag systemof claim 16, further comprising a second airbag cushion, wherein thefirst airbag cushion deploys out a lower portion of the dash of thevehicle and the second cushion deploys out an upper portion of the dashof the vehicle.